feat: Add session bus option for local testing and development

Introduced a `--use-session-bus` flag to optionally use the D-Bus
session bus instead of the system bus. This allows better flexibility
for local testing and development scenarios without requiring
system-level changes. Updated related classes and functions to respect
the new flag.

src/revpi_middleware/daemon.py

@@ -42,7 +42,7 @@ class MiddlewareDaemon:
         if self.bus_provider and self.bus_provider.is_alive():
             return
 
-        self.bus_provider = BusProvider()
+        self.bus_provider = BusProvider(use_system_bus=not pi.pargs.use_session_bus)
         self.bus_provider.start()
 
         log.debug("leave MiddlewareDaemon.dbus_start")